# get_num_par¶

sherpa.astro.ui.get_num_par(id=None)

Return the number of parameters in a model expression.

The get_num_par function returns the number of parameters, both frozen and thawed, in the model assigned to a data set.

Parameters: id (int or str, optional) – The data set containing the model expression. If not given then the default identifier is used, as returned by get_default_id. npar – The number of parameters in the model expression. This sums up all the parameters of the components in the expression, and includes both frozen and thawed components. int sherpa.utils.err.IdentifierErr – If no model expression has been set for the data set (with set_model or set_source).

get_num_par_frozen()
Return the number of frozen parameters.
get_num_par_thawed()
Return the number of thawed parameters.
set_model()
Set the source model expression for a data set.

Examples

Return the total number of parameters for the default data set:

>>> print(get_num_par())


Find the number of parameters for the model associated with the data set called “jet”:

>>> njet = get_num_par('jet')